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Late Quaternary channel and floodplain formation in a partly confined subtropical river, eastern Australia

journal contribution
posted on 2024-11-16, 03:38 authored by James S Daley, Jacky C Croke, Chris Thompson, Timothy CohenTimothy Cohen, Mark G Macklin, Ashneel Sharma
Along the eastern margin of Australia, hydrological variability reaches a peak in the subtropics of south-east Queensland and many rivers have entrenched characteristics. To address the nature of entrenchment and the relationship with adjacent alluvium, this paper presents the results of detailed chrono-stratigraphic analysis of alluvial units in the partly confined mid-reaches of Lockyer Creek, Australia. Four sites were investigated using topographic, sedimentological and chronological data. Radiocarbon and single grain optically stimulated luminescence dating indicate a large proportion of the valley fill reflects a major phase of aggradation of fine-grained alluvium from ca. 35 ka throughout the Last Glacial Cold Period. Synchronous incision of Pleistocene alluvial fills between 11.5 and 9.3 ka suggests the current entrenched Lockyer Creek formed in response to changes in late Quaternary climate. Holocene floodplains set within the entrenched Pleistocene valley floor have basal ages of ca. 7.5 ka, but whose proximal margins are still actively accreting. This Holocene fill has accreted over the mid- to late Holocene but overlaps with the contemporary hydrological regime. The sedimentary nature of the Holocene fill appears to be related to persistent antecedent controls in the form of bedrock and terrace constriction.

Funding

The big flood: will it happen again? If we could better predict the frequency of extreme flood events, would we be better prepared to safeguard human lives and settlements? This project provides a time-line of flood activity in the south east Queensland region extending back thousands of years using state-of-the-art dating techniques and seeks to identifiy those settlements most at risk

Australian Research Council

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History

Citation

Daley, J., Croke, J., Thompson, C., Cohen, T., Macklin, M. & Sharma, A. (2017). Late Quaternary channel and floodplain formation in a partly confined subtropical river, eastern Australia. Journal Of Quaternary Science, 32 (6), 729-743.

Journal title

Journal of Quaternary Science

Volume

32

Issue

6

Pagination

729-743

Language

English

RIS ID

116255

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